1. Field of the Invention
The present invention relates generally to the field of self-adhesive film assemblies for application to windows to make vision control panels, for example one-way vision panels having a design on one side which is not visible from the other side, the other side allowing through vision.
2. Description of Related Art
Vision control panels are well known, for example panels having a design superimposed on an opaque silhouette pattern as disclosed in U.S. U.S. Reissue Pat. No. 37,186 and panels having a design superimposed on a translucent “base pattern”, which enables the design to be illuminated from the other side of the panel, as disclosed in U.S. Pat. No. 6,212,805. Both of these patents disclose self-adhesive assemblies comprising a light-permeable film facestock layer, an adhesive layer and a removable protective film layer, sometimes referred to as a liner or release liner. Such self-adhesive assemblies include facestock film which is perforated vinyl, or vinyl cut into discrete, elongated areas, for example stripes, or non-perforated clear film.
In September 1993 Visual Technologies, Inc., N.C., USA, made public the application of an additional non-perforated backing layer to the perforated liner of a perforated self-adhesive vinyl assembly, as also disclosed in U.S. Pat. Nos. 5,773,110 and 5,609,938. The benefits of an assembly with a non-perforated backing layer are various, including the ability to hold the assembly with a vacuum suction device, for example on the bed of a screen printing press, and to prevent ink from a digital inkjet printing press passing though the perforation holes, for example onto a printing press platen. U.S. Pat. No. 5,858,155 discloses a non-perforated replacement liner applied to a perforated adhesive layer after removal of a temporary perforated liner, to achieve the same and additional benefits.
Such products are sometimes referred to as perforated base materials or perforated self-adhesive assemblies or perforated film assemblies or perforated self-adhesive films and are typically imaged by one of a number of printing techniques, including screen printing and various digital imaging methods, for example inkjet printing, electrostatic transfer printing and thermal mass transfer printing or sublimation. A perforated film assembly for subsequent application to the outside of a window typically has a white-on-black facestock, or a white facestock in conjunction with a black adhesive. An additional non-perforated backing layer is typically provided by a white self-adhesive “application tape” or by a heat-bonded film, for example a colorless, polypropylene film. A replacement liner is typically white or clear, typically a white, silicone-coated paper or a silicone-coated clear polyester. When imaged with a design, following removal of the liner and application to a window, the design is typically intended to be seen from outside the window, for example of a building or vehicle, illuminated by natural daylight. Designs such as advertisements or signs are typically seen, therefore, against a relatively dark background of the interior of the building or vehicle. Known techniques of “undercolor removal” of inks have been used to compensate for this background darkening effect, also disclosed in PCT/US96/09888.
Perforated static cling film assemblies with a non-perforated liner and no adhesive layer are also known.
U.S. Pat. No. 6,552,820 discloses a method of printing a vision control panel in which a transparent substrate is partially printed with an opaque print pattern, for example a print pattern of lines. An optical scanning device identifies leading and trailing edges of the select areas of printing and instructs a digital printing machine to print a superimposed layer, typically a design, on areas of the print pattern, for example a pattern of opaque white on black lines orientated perpendicular to the direction of primary movement of inkjet printheads, which are recognised in contrast to the transparent substrate that is unprinted between the opaque printed lines.
U.S. Pat. No. 5,250,336 (Greuse) discloses the use of a liner of contrasting color in a self-adhesive assembly in the field of kiss-cut, self-adhesive labels, to enable the quality of the cutting of the edges of kiss-cut labels to be more easily assessed following “weeding” of the surrounding unwanted facestock material.